This invention relates to novel and improved automatic locking gears or mechanical clutches; and more specifically relates to mechanical clutches of the type specifically adaptable for establishing driving connection between an axle and hub of the type employed in four wheel drives and other vehicles with multiple drive axles or drive shafts.
It is customary to employ mechanical clutches in four wheel drives which can be selectively activated in order to establish driving connection between the front drive axle and associated wheel hub in converting the vehicle to a four wheel drive mode. Mechanical clutches are often utilized in other applications to effect the desired driving connection between a driving member and another member to be driven. In four wheel drive applications, manual actuators are often employed to activate the clutch mechanism and effect the desired engagement between the drive and driven members and this approach is typified by the patent to Hegar U.S. Pat. No. 3,442,361 as well as the prior art patents referred to therein.
However, the present invention is more directly concerned with automatic clutches or locking gears which are responsive to the application of power or torque to the driving member, such as, the drive axle of a motor vehicle to effect a direct driving connection with the driven member or wheel hub and to maintain such engagement or axial location between the members regardless of the relative speed of the driving and driven members until torque has been removed from the drive member. In my earlier patent for automatic clutch with locking means, U.S. Pat. No. 3,217,847, an automatic mechanical clutch assembly is disclosed for automatically establishing engagement and disengagement between male and female locking elements in direct response to the torque applied to the driving member, the locking elements being broadly characterized by maintaining reversible engagement between the members; i.e., in either direction of rotation or application of torque to the driving member. Specifically, the clutch automatically effects the desired locking engagement through an actuator or shift mechanism which carries the male locking element and is shifted or caused to be cammed in an axial direction to advance the male locking members into slots associated with the driven member. As disclosed therein, the shift mechanism has cam portions normally retracted with respect to stationary, complementary cam portions on a fixed member so that when torque is applied to the shift member the cam portions rise along the surfaces of the stationary cam portion to advance the locking elements into the desired interengagement with one another. Once engaged, the complementary cam portions are separated with the shift mechanism imparting the driving torque of the drive axle through the locking element into the driven member or wheel hub. When torque is no longer applied to the axle, the shift member is biased or spring-loaded to cause the male locking members to be ejected from the slots. Thus, while the automatic clutch described in my hereinbefore referred to patent was effective to accomplish automatic engagement between the drive and driven members in the manner described, it is desirable to cause selective engagement between the members without the necessity of establishing positive locking engagement between male and female locking elements and in such a way as to greatly minimize the time interval required to effect full engagement and specifically the time period required for the respective cam portions and locking members to move into alignment with one another. Stated another way, it is desirable that the coacting cam portions maintain the same relative alignment even after the shift mechanism is advanced into position for driving engagement with the driven member; and in so moving into position does not require positive interconnection between male and female locking elements.